Dozens of fish species can survive out of water, ranging from mudskippers that actively walk and forage on mudflats to lungfish that can live buried in dried mud for years. These aren’t flukes of nature. Amphibious fish have evolved specialized ways to breathe air, move across solid ground, and keep their bodies from drying out.
Mudskippers: The Most Active Land Fish
Mudskippers are the closest thing to a fish that truly lives on land. Found along tropical coastlines in Africa, Asia, and Australia, they spend large portions of their day out of water, hunting insects, defending territory, and even climbing roots and rocks. They make short, frequent trips onto land rather than staying out for extended periods, shuttling back and forth between water and air throughout the day.
Their pectoral fins work like small arms. On land, mudskippers press their fins downward to push off the ground, generating thrust with a stride length of about 1.8 cm per step, roughly 40% longer than their fin stroke in water. The robust, muscular fin structure found across the goby family (mudskippers are gobies) likely predisposed these fish to walking in the first place. They also use their tail to catapult themselves in quick hops when they need to move fast.
Their eyes sit on short stalks on top of the head and can be raised or retracted, giving them a wide field of vision in air. The surface of their corneas has a mix of tiny structures normally seen in both aquatic and land-dwelling animals, helping them see clearly above water while resisting dryness. Terrestrial mudskipper species tend to have eyes positioned on top of their heads, while more aquatic species have eyes on the sides, like ordinary fish. Mudskippers breathe primarily through their skin and the lining of their mouth and throat, which they keep moist by rolling in puddles or mud.
Lungfish: Years of Survival Without Water
African lungfish hold the record for the longest time any fish can survive on land. When rivers and lakes dry up during seasonal droughts, these fish burrow into the mud and enter a dormant state called aestivation. They secrete a thick layer of mucus that hardens into a thin, papery cocoon around their body, leaving only a small opening at the mouth connected to a narrow passage to the surface for breathing.
During aestivation, lungfish stop eating and excreting waste entirely. Their metabolic rate drops dramatically, and they switch from producing ammonia (which requires water to flush out) to producing urea, which they can safely store in their tissues. Their water loss drops substantially within the first week and stays low for months. They can remain in this state for several years, losing more than 10% of their body mass in the process. When the rains finally return, they resume normal movement and feeding within a single day.
Lungfish have actual lungs, not just modified swim bladders. They gulp air at the surface even when submerged, making them obligate air breathers. Some species will drown if held underwater and prevented from reaching the surface.
Snakeheads: Overland Colonizers
Northern snakeheads can breathe air using a chamber above their gills and are capable of crawling short distances across land to reach new bodies of water. They wriggle their bodies in a snake-like motion, which is how they got their name. While the distances they cover on land are short, this ability has contributed to their reputation as an aggressive invasive species in the eastern United States. Even a small gap between two ponds or streams can be enough for a snakehead to colonize a new ecosystem.
Climbing Perch and Other Labyrinth Fish
Climbing perch, gouramis, and bettas all belong to a group called anabantoids, which share a specialized air-breathing structure called the labyrinth organ. This organ sits in a pair of chambers above the gills and consists of a complex bony structure lined with thin, heavily blood-supplied tissue that extracts oxygen directly from air. It works like a simple lung, allowing these fish to survive in stagnant, oxygen-poor water and, in the case of climbing perch, to leave the water entirely.
Climbing perch can travel across land using their gill plates and fins to drag themselves forward. They’ve been documented crossing roads and fields in Southeast Asia during rainy conditions, moving between ponds and rice paddies.
Mangrove Killifish: Hiding in Logs
The mangrove rivulus is a small killifish found in mangrove forests from Florida to Brazil. When conditions in the water become unfavorable, these fish flip themselves out onto land and shelter inside rotting logs, crab burrows, or leaf litter. One trigger for leaving the water is temperature: mangrove rivulus emerge to escape warm water and initially benefit from evaporative cooling on land, where they actively seek out cooler spots.
This species can survive out of water for weeks at a time. During extended land stays, their gills physically remodel, becoming less useful for aquatic breathing but better suited to air. This remodeling takes days to weeks to develop, which is why it’s found in species that stay out for long stretches rather than in mudskippers, which hop in and out of water too frequently for such slow changes to be useful. The mangrove rivulus can emerge onto land at any life stage.
Walking Catfish and Eels
Several catfish species have impressive land survival abilities. Clarias catfish, commonly called walking catfish, use their pectoral fin spines to drag themselves across ground. Like snakeheads, they have an accessory breathing organ that lets them extract oxygen from air. They can survive months without water during droughts. Walking catfish are invasive in Florida, where they’ve been spotted crossing roads between canals.
The singhi catfish from South Asia similarly survives terrestrial conditions by switching its waste processing to urea production, the same strategy lungfish use. Misgurnus loaches, also called weather loaches, can survive months out of water by absorbing oxygen through their intestinal lining.
Eels, while not true amphibious fish in the same way, can survive out of water for hours and cross short stretches of wet grass or mud. European and American eels do this during migrations, particularly as juveniles moving upstream.
Why Fish Leave the Water
Fish don’t end up on land by accident. The triggers vary by species, but they generally fall into a few categories: escaping low oxygen levels, avoiding predators, finding food, escaping high temperatures, or surviving drought. Intertidal species like mudskippers and pricklebacks are exposed to air regularly by the tides and have adapted to take advantage of the food resources on exposed mudflats and rocks.
For freshwater species, seasonal drought is the most common driver. Lungfish and walking catfish live in environments where water disappears for months at a time, so land survival isn’t optional. It’s the difference between life and death. The mangrove rivulus offers a more nuanced case: it leaves water voluntarily when conditions are merely uncomfortable, not life-threatening, suggesting that some fish actively prefer land under certain circumstances.
How They Breathe Without Gills Underwater
Fish on land face an immediate problem: gills collapse without water to support them, drastically reducing the surface area available for gas exchange. Amphibious fish solve this in several ways, often using more than one at a time.
Skin breathing (cutaneous respiration) is the most widespread method. Mudskippers, mangrove killifish, and eels all absorb oxygen through their moist skin. This works only as long as the skin stays wet, which is why many of these species stay close to water or seek out humid microhabitats like logs and burrows.
Lungfish have true lungs. Labyrinth fish have their specialized bony breathing chambers. Walking catfish and snakeheads have accessory organs above their gills. Some species, like certain loaches, can even absorb oxygen through the lining of their gut by gulping air. Each of these solutions evolved independently in different fish lineages, making amphibious life one of the most repeatedly reinvented strategies in fish evolution.